contextswhile

Contextswhile is a proposed control-flow construct that combines context management with an iterative, while-like loop. It enables acquiring a resource or set of resources and guaranteeing their release in relation to the loop’s execution. In design variants, the context may be established for the entire loop or re-established at the start of each iteration.

Semantics: Each iteration may begin by entering a context; the loop body runs; the context is exited at the end of the iteration. In some variants, a single context spans the whole loop; in others, a fresh context is opened per iteration. The primary objective is deterministic cleanup even if the loop exits early or via an exception, ensuring resources do not leak.

Implementation: Contextswhile is not part of a standard language feature in mainstream languages, but can be realized as library constructs, macros, or compiler extensions. It draws on established ideas from context managers, resource acquisition is initialization (RAII), or try-with-resources patterns. Performance considerations include potential overhead per iteration and the cost of frequent context setup and teardown, which implementations may optimize or batch.

Use cases: It is especially useful when an operation requires reliable resource management across iterations, such as iterating over a stream or device, performing transactional operations, or handling temporary files. When well designed, contextswhile variants can prevent resource leaks and simplify error handling, though they may introduce additional complexity or context churn if overused.

See also: Context manager, while loop, resource management, RAII, try-with-resources, deterministic finalization.